Lens of photographic cameras, picture projecting apparatus, and other like optical devices



SR StARCH ROOM July 7 14112 5 1,813,439

v 7, 7 V u Am .aOJECTING APPARATU AND OTHER E OPTICAL DEVICES iled larch1925 CIVVE/V MA Patented July 7, 1931 UNITED STATES PATENT OFFICE LENSPHOTOGRAIHIC CAIERAS, PICTURE PROJECTING APPARATUS, AND OTHER LIKEOPTICAL DEVICES Application filed. larch 18, 1925. Serial No. 18,508.

This invention relates to cameras for taking still and motion pictures,picture projecting apparatus-such as are used for throwln pictures upona screen-and like optical evices (all of which are hereinafter deemed tobe included when reference is made to camera) and has for its objectimprovements whereb a sharper definition an greater life-like p asticityis obtained.

I have found thatthis purpose is served by providing the camera or likeap aratus with a supplementary stop locat at or near the centre of theaperture and in a different plane from the usual marginal stop. Inthisway different areas of the lens are reserved for the rays reflected fromobjects in corresponding areas of the field and as a result the efl'ectthat results from other rays passin throu h the same area of the :0lens, is avoi ed. ith this arrangement the rays reflected from objectson or near the optical axis pass through the annular aperture betweenthe central and marginal stops and through that part of the lensbehinddtwhile the rays reflected from objects in other arts of the fieldpass through the more or ess crescent-shaped aperture formed'between thesame stops (according to the direction of the said rays) and the portionof the lens upon which such ra 5 fall, all of which will be refracted byt e lens in the well-known way and focussed in their pro r positions ona plate or screen or equlva ent part situated in the focal plane.

In this way a stronger image of objects is projected onto the plate orscreen giving them a more sharply defined outline and producing greaterplasticity.

According to one mode of carrying this 40 invention into practice asupplementary stop preferably in the form of a disc is situated on ornear the optical axis of the lens. This stop is smaller than theaperture formed by the usual marginal stogeand may be 0 aqueor-semi-opaque, may circular or 0 any other suitable shape and ma insome cases be situated eccentrically. W ith this arrangement an image ofthe objects on the optical axis and near it or the meridian 60 on whichthe screen is situated is projected by those rays reflected therefromthat pass through the aperture constituted by the marginal and centralstops te-the lens while the rays of light reflected from other objectsin the field passes obliquely through the said aperture to portions ofthe lens determined by the position of eachsuch'ob'ect.

By locating the aforesai supplementary central stop at the back of thelens surface when a single lens islused or in front of the backcomponent of a compound lens, flare resulting from internal reflectionis reduced.

A normal orifice stop of known kind may be employed with thesupplementary central stop which latter may be applied to either thefront or back surface of the lens, and when two or more lenses areemployed all or any of them may be similarly provided with similarsupplementary stops, the dimensions of which may vary. In some cases thesaid supplementary stop or stops may be suitably supported at a point orpoints in front of or behind the lens or lenses and their respectivepositions may be adjustable.

. It is of course understood that shutters, diaphragms, focusing meansand means for properly positioning the films il Ild. platesor acomblnation of any of thesedevice'sl may be employed withthe'improyflnts herein before described.

I will now proceed to more particularly describe my invention with theaid ofthe accompanying drawings, in which Fig. l is a diagrammaticallongitudinal section through the improved camera showing one arrangementof the lenses and stops,

igs. 2 and 3 are longitudinal sections through the lenses showingdilferent arrangements of the stops,

F 1g. 4 is a front view of the marginal and central stops,

Fig. 5 is anoblique front view of the said stops, and I Fig. 6 is adiagrammatical longitudinal section through a single lens showing thearrangement of the stops.

' According to the arran ement shown in Fig. 1 the camera is providedwith a compound lens comprising the components a b each of which consistof two lenses 0 d e f. 1m

A marginal stop 9 of known kind is situin a'plane between the atedbetween the hHpgnentwLL h and a central'sto is applied to the front faceof fiie lens f of the rear component b.

With this arrangement the light reflected from an object on or near theoptical axis of the system will pass through the annulus z in F ig. 4between the outer edge of the central stop It and the inner edge of themarginal stop 9' whereas the rays of light reecte rom 0 'jects nearer tothe margin of the field will pass through the aperture j shown in Fig. 5which will be more or less crescent-sha ed according to whether thedirection of said rays is more or less inclined to the axis of thesystem.

According to the arrangement shown in Fig. 2 the sup lemental stop it issupported in a position between the marginal stop 9 and the rearcomponent 'b of the lens. In

this case the supplemental stop it may be sup orted by wires k orequivalent parts ex ten ing from a ring 1 whose position may be changedso as to adjust the position of the stop h.

To enable this adjustment to be conveniently made the ring Z may beconnected to an outher sleeve m by rlvets n that pass through slots 0 inthe lens holder.

According to the construction shown in Fig. 3 the supplemental stop hmay be so ported in'front of the component a of the ens.

When a single lens is employed the stop h is preferably applied to itsrear surface as is shown in Fig. 6.

I claim:

1. Apparatus for projectin the image of objects to a surface situate inthe focal plane of a lens, comprising a lens, a mar ginal stop formedwith an aperture, and a supplementary stop of smaller diameter than saidaperture located near the surface of the lens remote from the source oflight and in a plane between the marginal stop and the focal plane andnear the optical axis of the lens and being adjustable toward or fromsaid marginal stop.

2. Apparatus for projectin the image of objects to a surface situate .inthe focal plane of a lens, com rising a lens, a marginal stop formedwith an aperture, and a supplementary stop of smaller diameter than saidaperture, located near the surface of the lens remote from the source oflight and in a plane substantially removed from the radial plane of saidmarginal stop and near the optical axis of the lens.

3. Apparatus for projecting the image of objects to a surface situatedin the focal plane of a lens,'comprising a lens, 8. marginal stop formedwith an aperture, and a supplementary stop of smaller diameter than saidaperture, located near the surface of the lens remote from the source oflight and t e focal plane, and near the optica axis of the lens.

- ihApparatus for project in the ima e of ob ects to a surface situatein the ocal plane of a lens comprising a lens, and a central stoplocated near the surface of the lens remote from the source of light andof sufficient area to 'stop off internal reflections within the lens butsufiicien-tly limited to allow of oblique rays emanating from thecentral portion of objects to be transmitted and refracted around it toform'a complete image of the whole object during photography orprojection.

5. Apparatus .for projecting the image of ob ects onto a surfacesituated in the focal plane of a lens, comprising a lens, a marginal stoformed with a large central aperture, an a supplementary stop of smallerdiameter than said aperture located near the surface of the lens remotefrom the source of light.

In testimony whereof, I have signed my name to this specification atLondon this 27th day of Februar 1925.

. CLYDfi JAY COLEMAN.

